Summary Calgary Flight Training Centre Cessna 172, C-GVLO, was cleared to follow another aircraft backtracking on runway 25 at Calgary International Airport, Alberta. The Calgary Tower air traffic controller told the pilot that he was number one for take-off. Following the clearance for C-GVLO to backtrack runway 25, the pilot of an Airbus A319, Air Canada Flight 185 (ACA185), holding on runway 16, was cleared for take-off. At that time, both ACA185 and C-GVLO commenced take-off; C-GVLO without take-off clearance. The pilot of C-GVLO called rolling, and the controller immediately advised him to abort; however, the pilot continued the take-off. At 1818:12 mountain standard time (MST), the controller advised ACA185 to abort the take-off because of the traffic taking off from runway 25. ACA185 was at about 120 knots and came to a stop with about one-half of the runway length remaining. Emergency Response Services (ERS) were requested to respond to ACA185 as a precaution because of possible hot brakes. Ce rapport est galement disponible en franais. Other Factual Information The pilot of C-GVLO was a licensed private pilot with approximately 75 to 80 hours of flight experience. He had acquired his private licence in November 1998 and was in the process of building his flight time in order to qualify for a commercial licence. He had flown four to five hours in the previous ten days. The flight was planned to be an informal upper air work review flight using a CFTC rental aircraft in a training area to the west of Calgary. As C-GVLO approached runway 25, the pilot of another aircraft already backtracking the runway advised the tower that he was in no hurry and that C-GVLO could depart first. The controller issued backtrack clearance to C-GVLO, and, after being told that C-GVLO would backtrack only about 400 feet, advised C-GVLO that he was number one because the other aircraft was to backtrack all the way to the end. The distance from taxiway C, from which both aircraft had entered runway 25, to the button of runway 25 is approximately 3 400 feet, and the distance from taxiway C to runway 16/34 is approximately 600 feet. Backtracking 400 feet provided C-GVLO about 1 000 feet from the beginning of his take-off run until reaching the intersection of runway 16/34. The Calgary Tower air controller had ten years' experience as a controller and had worked in Calgary Tower for five years. He was working the fifth day of his shift cycle and had been on duty for four and a half hours since the beginning of his shift; it had been one hour since his last break. Staffing in the tower met unit requirements for Saturday operations. Because of lower traffic volumes on Saturdays, the tower coordinator position is not staffed, requiring the air controller to manipulate the electronic data strip display and to perform other communications and coordination functions. This required that he divert his attention to functions normally performed by another person and to administrative activities inside the tower cab. These extra requirements reduced the amount of time the controller could devote to monitoring activities outside the tower cab on Calgary's three runways. Traffic at the time was described as light, and visibility was reported to be 40 statute miles. The NAV CANADA Air Traffic Control (ATC) Manual of Operations (MANOPS) provides authorization for controllers to position aircraft on intersecting runways for take-off as follows: 336.2 A. Note: Caution should be exercised to prevent confusion among the involved aircraft. 336.2 A. Note: Caution should be exercised to prevent confusion among the involved aircraft. all aircraft are visible to the airport controller; and traffic information is given to the second and subsequent aircraft in the departure sequence. 336.2 A. Note: Caution should be exercised to prevent confusion among the involved aircraft. all aircraft are visible to the airport controller; and traffic information is given to the second and subsequent aircraft in the departure sequence. Article 336.1 specifies the phraseology to be used when sequencing a departing aircraft that is not number one for take-off, as follows: Aircraft Identification. Number (sequence). Type and position of preceding departure. Aircraft Identification. Number (sequence). Type and position of preceding departure. 336.1 Phraseology: For intersecting runways/flight paths - NUMBER TWO FOR DEPARTURE, TRAFFIC SEVEN TWENTY SEVEN DEPARTING RUNWAY (number). After C-GVLO advised the controller that he would backtrack runway 25 for 400 feet, the controller replied that C-GVLO would be number one because the other aircraft on runway 25 was going to the end of the runway. According to the example given in ATC MANOPS, the phraseology used should have been, Victor Lima Oscar, number two for departure, traffic A319 departing runway 16. No mention was made to C-GVLO that ACA185 would be first to depart. Twenty-one seconds later, at 1817:24(1), after performing the mandatory runway scan to ensure the runway was clear, the controller issued take-off clearance to ACA185. The controller then diverted his attention to the tower console to find the computer mouse used to record departure times in the automated aircraft movement system. The controller did not observe the simultaneous movement of both of the aircraft until the pilot of C-GVLO advised that he was rolling on runway 25 at 1818:06. The angular displacement, when viewed from the tower, between the end of runway 16 from which ACA185 was departing and the point on runway 25 from which C-GVLO was departing, is approximately 135 degrees. The pilot of C-GVLO was not aware that ACA185 was in position on runway 16, and did not hear the take-off clearance issued to that aircraft, even though the clearance was issued on the same frequency that C-GVLO was monitoring. Believing he had authorization to take off, he applied power and began the take-off roll. He had second thoughts, however, and momentarily applied brakes. He looked to his right and saw ACA185, but was unsure whether that aircraft was moving. He convinced himself that he could not stop before runway 16, in any event, and continued the take-off. After advising the tower that he was rolling, he did not hear the instruction to stop or abort his take-off. Article 337.1 specifies the phraseology to be used when it becomes necessary to cancel a take-off clearance. before the aircraft has started to roll - TAKE-OFF CLEARANCE CANCELLED; after the aircraft has started to roll - ABORT TAKE-OFF. 337.1 Note: An aborted take-off is an emergency procedure employed in situations where to continue would present a grave hazard to the aircraft. A controller-initiated abort of take-off should be viewed as an extreme measure to be used only where there is no clear alternative course of action. before the aircraft has started to roll - TAKE-OFF CLEARANCE CANCELLED; after the aircraft has started to roll - ABORT TAKE-OFF. 337.1 Note: An aborted take-off is an emergency procedure employed in situations where to continue would present a grave hazard to the aircraft. A controller-initiated abort of take-off should be viewed as an extreme measure to be used only where there is no clear alternative course of action. NAV CANADA Air Traffic Services Information Bulletin 105, dated 09 March 1981, enlarges on the information provided in MANOPS article 337.1 Note above and reminds service providers that: In rare cases, controllers may feel compelled to instruct pilots to abort take-off due to impending collision (runway incursion by vehicles or other aircraft) or potential loss of airborne separation. Regardless of the initiative for such action, an aborted take-off, if executed, will be undertaken with maximum effort. This places tremendous strain on both aircraft and crew and the procedure has potential for hazard which may be greater than that faced by continuing the take-off. This is particularly true in the case of an abort initiated by ATC for reasons of eroded IFR separation. As a controller, when faced with a situation suggesting the need for an aborted take-off there are many factors to consider and little time in which to consider them. It is possible to imagine such a variety of circumstances that to pre-plan a response for each of them would not be practicable. It is, in the final analysis, a matter of instant judgement. The controller issued urgent instructions to C-GVLO to abort take-off using the phraseology in accordance with ATC MANOPS article 337.1. When he received no response or indication of compliance, he did not know whether C-GVLO would comply, and he was concerned that, if the pilot did stop, the smaller aircraft might stop on runway 16 in the path of ACA185. He then requested ACA185 to abort take-off as well. The distance from the button of runway 16 to its intersection with runway 25 is approximately 9 800 feet. Under the existing environmental and aircraft conditions, an Airbus A319 taking off at Calgary, assuming normal operations, would require 4 612 feet to become airborne and would cross runway 25 (approximately 9 000 feet from the beginning of the take-off roll) at a height of 600 feet. A Cessna 172, in the conditions of the occurrence, would require approximately 850 feet to become airborne, and 1 000 feet after beginning its take-off roll would be at less than 200 feet above ground. The pilot of C-GVLO reported that several issues associated with this occurrence were different from his expectations. He was planning on doing his air work in the west practice area and was anticipating having to contact Springbank Tower on the way to the practice area, an area he had been to only three times previously. He had originally expected to taxi for runway 16, knowing it to be the active runway; when he was offered runway 25, he accepted. On reaching the hold point for runway 25, he was immediately and unexpectedly offered the opportunity to backtrack runway 25 and to depart before the Cessna ahead, which he accepted. This flight was only the second time since acquiring his licence that he had flown with a passenger on board; the one previous time had been in late October 1998, nearly four months prior. His experience was that, normally, when cleared to line up on the runway, but not cleared for take-off, he would hear the expression taxi to position or something similar. In this case, to clear C-GVLO onto the runway, the controller used the phraseology, Victor Lima Oscar, right turn, back track to position runway two five, how far back do you require? The pilot of C-GVLO reported that he had previously, during the busy few seconds when an ab initio pilot is positioning on a runway for take-off, had trouble distinguishing the executive order to take off from all of the other verbiage which is issued by the control agency. In these circumstances, he had been prompted to take off without delay by the instructor. Having taken flying training in Calgary, a busy airport, he was accustomed to expediting the take-off process once on the runway. A new chapter (Exercise 30) in the fourth edition (1999) of the Transport Canada (TC) Flight Training Manual now covers radio communications in some detail, and the topic is mentioned briefly in the TC Flight Instructor's Guide. The Flight Training Manual warns pilots that By keeping a good listening watch on the frequency you maintain situational awareness, which assists in identifying potential traffic conflict. The CFTC does not target radio procedures in the private pilot syllabus and expects students to pick up the necessary expertise as they progress through the flying training lesson plans.